<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Document</title>
    </head>
    <body>
        <script>
            let obj = {
                name: 'wangjin',
                obj: {
                    say: function()  {
                        // console.log('i can say');
                        console.log(this); // obj
                    },
                },
            };
            function sing() {
                // console.log('i can sing!');
                console.log(this); // window
                let obj = {
                    name: 'wangjin',
                    obj: {
                        say: () => {
                            // console.log('i can say');
                            console.log(this); // window 
                        },
                    },
                };
                return obj;
            }
            sing().obj.say();  
            // obj.obj.say();
            // window.sing()
            // console.log(obj.say);
        </script>
    </body>
</html>
